Weishampel's most well known published work is The Dinosauria University of California Press; 2nd edition (December 1, 2004).
An authority on Ceratopsians, he has also authored several papers and textbooks on hadrosaurs and sauropods, and is a co-editor of The Dinosauria, widely considered the definitive scholarly reference on dinosaurs.
The Dinosauria superorder was divided into the two orders Ornithischia and Saurischia by Harry Seeley in 1887.